/*******************************************************************************************[Map.h]
Copyright (c) 2005-2010, Niklas Een, Niklas Sorensson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/

/*
Requires copy constructor and assignment operator to be defined for the key and
datum types, (plus default constructor unless null value is passed to constructor)
*/


#ifndef Map_h
#define Map_h

#include "VecAlloc.h"
#include "Hash_standard.h"


//=================================================================================================
// Map implementation:


template <class K, class D, class Par = Hash_params<K> >
class Map
{

    struct  Cell {
        K       key;
        D       datum;
        Cell*   next;
    };

    VecAlloc<Cell>  alloc;
    Cell**          table;
    int             capacity;
    int             nelems;
    const D         D_null;

    //---------------------------------------------------------------------------------------------

    int index(const K& key) const {
        return Par::hash(key) % capacity; }     // (this is done in 'rehash()' as well)

    int getCapacity(int min_capacity) {
        int     i;
        for (i = 0; prime_twins[i] < min_capacity; i++);
        return prime_twins[i]; }

    void init(int min_capacity) {
        capacity = getCapacity(min_capacity);
        nelems   = 0;
        table    = xmalloc<Cell*>(capacity);
        for (int i = 0; i < capacity; i++) table[i] = NULL; }

    void dispose(void) {
        for (int i = 0; i < capacity; i++){
            for (Cell* p = table[i]; p != NULL;){
                Cell*    next = p->next;
                p->key  .~K();
                p->datum.~D();
                alloc.free(p);
                p = next; } }
        xfree(table);
    }

    void rehash(int min_capacity) {
        int     new_capacity = getCapacity(min_capacity);
        Cell**  new_table    = xmalloc<Cell*>(new_capacity);
        for (int i = 0; i < new_capacity; i++) new_table[i] = NULL;

        for (int i = 0; i < capacity; i++){
            for (Cell* p = table[i]; p != NULL;){
                Cell*    next = p->next;
                unsigned j    = Par::hash(p->key) % new_capacity;
                p->next = new_table[j];
                new_table[j] = p;
                p = next;
            }
        }
        xfree(table);
        table    = new_table;
        capacity = new_capacity;
    }

    D& newEntry(int i, const K& key, const D& value) {
        if (nelems > capacity / 2){
            rehash(capacity * 2);
            i = index(key); }
        Cell* p = alloc.alloc();
        new (&p->key)   K(key);
        new (&p->datum) D(value);
        p->next  = table[i];
        table[i] = p;
        nelems++;
        return p->datum; }

    //---------------------------------------------------------------------------------------------

public:
    // Types:
    typedef K Key;
    typedef D Datum;

    // Constructors:
    Map(void)                        : D_null()     { init(1);        }
    Map(const D& null)               : D_null(null) { init(1);        }
    Map(const D& null, int capacity) : D_null(null) { init(capacity); }
   ~Map(void)                                       { dispose();      }

    // Size operations:
    int      size  (void) const { return nelems; }
    void     clear (void)       { dispose(); init(1); }

    // Don't allow copying:
    Map<K,D,Par>& operator = (Map<K,D,Par>& other) = delete;
                  Map        (Map<K,D,Par>& other) = delete;

    //---------------------------------------------------------------------------------------------
    // Export:


    void domain(vec<K>& result) const {
        for (int i = 0; i < capacity; i++)
            for (Cell* p = table[i]; p != NULL; p = p->next)
                result.push(p->key); }
    void range (vec<D>& result) const {
        for (int i = 0; i < capacity; i++)
            for (Cell* p = table[i]; p != NULL; p = p->next)
                result.push(p->datum); }
    void pairs (vec<Pair<K,D> >& result) const {
        for (int i = 0; i < capacity; i++)
            for (Cell* p = table[i]; p != NULL; p = p->next)
                result.push(Pair_new(p->key, p->datum)); }


    //---------------------------------------------------------------------------------------------
    // Main:


    // Searches for 'key' in the hash table. Returns the value of 'found' or 'notfound'.
    // 'found' may use 'Cell* p' refering to the cell that was found; 'notfound' may use
    // 'unsigned i', the index position in the table.
    #define SEARCH(found, notfound) \
        unsigned    i = index(key); \
        for (Cell* p = table[i]; p != NULL; p = p->next){ \
            if (Par::equal(p->key, key)) \
                return found; \
        } \
        return notfound;


    // Returns a reference to existing or newly created element.
    D& ref(const K& key) {
        SEARCH(  p->datum
              ,  newEntry(i, key, D_null)
              );}

    // Sets 'key' to 'value' and returns 'value'.
    const D& set(const K& key, const D& value) {
        SEARCH(  p->datum = value
              ,  newEntry(i, key, value)
              );}

    // Sets 'key' to 'value' IF not already set. Returns the value at 'key' after operation (new or old).
    const D& weakSet(const K& key, const D& value) {
        SEARCH(  p->datum
              ,  newEntry(i, key, value)
              );}

    // Same as 'set()' but 'key' must not be set already.
    const D& add(const K& key, const D& value) {
        SEARCH(  (PANIC("Tried to add an already existing element to the hashtable."), D_null)
              ,  newEntry(i, key, value)
              );}

    // Same as 'has' but returns through reference a pointer to the element (if it exists).
    bool peek(const K& key, D*& result) const {
        SEARCH(  (result = &p->datum, true)
              ,  false
              );}

    // Same as 'has' but returns through reference the element (if it exists).
    bool peek(const K& key, D& result) const {
        SEARCH(  (result = p->datum, true)
              ,  false
              );}

    // Returns datum at 'key' (or the null value if none)
    const D& at(const K& key) {
        SEARCH(  p->datum
              ,  D_null
              );}

    // Same as 'at' but 'key' must contain a value.
    const D& find(const K& key) {
        SEARCH(  p->datum
              ,  (PANIC("Tried to find non-existing element in hashtable."), D_null)
              );}

    // Have 'key' been set?
    bool has(const K& key) {
        SEARCH(  true
              ,  false
              );}

    // Get the current equal (but not same) key used for 'key'.
    const K& findKey(const K& key) {
        SEARCH(  p->key
              ,  (PANIC("Tried to find non-existing element in hashtable."), *(K*)NULL)
              );}

    // Exclude 'key' if exists.
    bool exclude(const K& key) {
        unsigned    i = index(key);
        for (Cell** pp = &table[i]; *pp != NULL; pp = &(*pp)->next){
            if (Par::equal((*pp)->key, key)){
                Cell*   p = *pp;
                *pp = (*pp)->next;
                nelems--;
                p->key  .~K();
                p->datum.~D();
                alloc.free(p);
                return true; }
        }
        return false;
    }

    // Same as 'exclude' but 'key' must exist.
    void remove(const K& key) {
        if (!exclude(key)) PANIC("Tried to remove non-existing element from hashtable."); }


    #undef SEARCH

};


//=================================================================================================

#endif
